Control units are used in large numbers in many fields of technology. One especially important field of application is for engine control in automobiles and for controlling the jet engines of aircraft.
A method for influencing a control unit is known from the document DE 10 2004 027 033 A1. Data of the control unit is mirrored in the memory area of the influencing device by means of an influencing device using a control unit-debug interface and a memory area embodied in the influencing device, and data is also mirrored back into the memory of the control unit, again using the control unit-debug interface. In one embodiment, the data is received by a coordination unit in the influencing device and is provided with a time stamp for a chronological classification. In addition, the coordination unit has terminals for internal and external trigger signals by means of which it is possible to activate corresponding subunits in the influencing device and to trigger a bypass routine, for example.
The document DE 10 2006 062 555 A1 discloses a method for observing a control unit in which an influencing device for observation of a control unit comprises at least one microcontroller, at least one memory and at least one debug interface. With the debug interface, which has a so-called trace functionality, it is possible to monitor addresses to be observed.
From the previous methods, it has been found that manipulation of control unit functions is time-consuming and is often performed via a so-called external bypass method, in which interrupt processing in an external manipulation device is prompted by the control unit by means of trigger pulses transmitted outward in the execution of the program by means of service calls that are fixedly defined in the program of the control unit. As part of the interrupt processing, the additional values needed for calculation are transmitted to the manipulation device. After the calculation in the manipulation device, the altered variables are sent back to the control unit. Since the service calls are fixedly tied into the program code of the control unit, any subsequent change in the service call points is very complicated and can be performed subsequently only with a great expenditure of effort, depending on the control unit manufacturer, because a pre-existing control unit program would have to be translated again, for example. Furthermore, the size of the memory required is increased by the service call points, which has a negative effect on the processing rate of control unit programs.